121 lines
2.9 KiB
C
121 lines
2.9 KiB
C
/*
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* clk-divider-table.c - generic barebox clock support. Based on Linux clk support
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*
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* Copyright (c) 2012 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <common.h>
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#include <io.h>
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#include <malloc.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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struct clk_divider_table {
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struct clk clk;
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u8 shift;
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u8 width;
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void __iomem *reg;
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const char *parent;
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const struct clk_div_table *table;
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int table_size;
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int max_div_index;
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};
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static int clk_divider_set_rate(struct clk *clk, unsigned long rate,
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unsigned long parent_rate)
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{
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struct clk_divider_table *div =
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container_of(clk, struct clk_divider_table, clk);
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unsigned int val;
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int i, div_index = -1;
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unsigned long best = 0;
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if (rate > parent_rate)
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rate = parent_rate;
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if (rate < parent_rate / div->table[div->max_div_index].div)
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rate = parent_rate / div->table[div->max_div_index].div;
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for (i = 0; i < div->table_size; i++) {
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unsigned long now = parent_rate / div->table[i].div;
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if (now <= rate && now >= best) {
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best = now;
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div_index = i;
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}
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}
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val = readl(div->reg);
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val &= ~(((1 << div->width) - 1) << div->shift);
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val |= div_index << div->shift;
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writel(val, div->reg);
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return 0;
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}
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static unsigned long clk_divider_recalc_rate(struct clk *clk,
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unsigned long parent_rate)
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{
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struct clk_divider_table *div =
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container_of(clk, struct clk_divider_table, clk);
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unsigned int val;
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val = readl(div->reg) >> div->shift;
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val &= (1 << div->width) - 1;
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if (val >= div->table_size)
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return 0;
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return parent_rate / div->table[val].div;
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}
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static struct clk_ops clk_divider_table_ops = {
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.set_rate = clk_divider_set_rate,
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.recalc_rate = clk_divider_recalc_rate,
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};
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struct clk *clk_divider_table(const char *name,
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const char *parent, void __iomem *reg, u8 shift, u8 width,
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const struct clk_div_table *table, unsigned flags)
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{
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struct clk_divider_table *div = xzalloc(sizeof(*div));
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const struct clk_div_table *clkt;
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int ret, max_div = 0;
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div->shift = shift;
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div->reg = reg;
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div->width = width;
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div->parent = parent;
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div->clk.ops = &clk_divider_table_ops;
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div->clk.name = name;
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div->clk.parent_names = &div->parent;
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div->clk.flags = flags;
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div->clk.num_parents = 1;
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div->table = table;
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for (clkt = div->table; clkt->div; clkt++) {
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if (clkt->div > max_div) {
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max_div = clkt->div;
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div->max_div_index = div->table_size;
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}
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div->table_size++;
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}
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ret = clk_register(&div->clk);
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if (ret) {
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free(div);
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return ERR_PTR(ret);
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}
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return &div->clk;
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}
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